Grinding-machine



APffucATln mm n n/9.1.91?,

AQ SCRIVENOR. GRINDING MACHIN.

' Patented June 28,1921

GRINDING MACHINE.

APPLICATloN FILED MAY9,1917.

1,382,747. Patented June 28, 1921.

5 SHEETS-SHEET 3.

A. SCRIVENOR.

GRINDING MACHINE.l APPLICATION FILED M AY 9. IQII.

@Hoff/w11 A. scmvENoR. GRINDING MACHINE. 'APPLICATION FILED MAY 9, 19K?.

Patented June 28, 1921.

5 SHEETS-SHEET 5.

IHM/Q14 UNITED STATES N PATENT ARTHUR SCRIVENOR, OF RICHMOND,r VIRGINIA.

VGRINDIIN'G-MIACHIN E.

VRichmond, in the county-of Henrico and State of Virginia, have invented certain new and useful Improvements in Grinding-Machines, of which the following is a specication, reference being had therein tothe accompanying drawing.

My invention' relates to machines for grinding cutting tools of cylindrical shape, and is described 'as used for grinding the threads or teeth of steel burs used in dressing grindstones, but it isv not limited to such use.

Objects of the invention are to provide means, for grinding spiral threads of several'pitches atthe same grinding or work speed, and without loss of time in the changing of the machine from one pitch to another', for quickly setting the work so that the threads to be ground may be quickly brought into proper relation with the grinding means; for` accurately indexing the work; for rapidly bringing the work into and, out of engagement with the grinding means during the process of'grinding.'

In the accompanying drawings, igs. I, and II show the' machine in plan and side elevation respectively. Fig. III shows an example of cylindrical work having a spiral thread or cut. Fig. IV is a longitudinal section of the work spindle, mounted in its bearings. Fig. V is a diagram showing the arrangement of the gearing driving the'y spindle shown in Fig. IV; and Fig. VI is an end view ofthe same arrangement. `Fig. VII'is a detail view of the grinding motor bracket,v partly in section; Fig. VIII is a. detail, in plan, of the knee supporting the grinding motor bracket; and Fig., IX is a detail showing the grinding motor in operative position. 1 g I In Figs. I and II the numeral 1 designates the bedl of the machine. In Fig. II the lower part ofthe bed is not shown. To the side ofthe bed is bolted'a bracket 2 for the purpose of carrying a motor 3*, orother driving mechanism. 4Driven by thev motor `is a worm gearing contained in the housing The worm is carried by the shaft 5 which may be-gdireotly connected, or by means' of a iiexible coupling, vwith the shaft of vmotor 3;

and the worm wheel is carried'by the sleeve of a friction clutch 6, which sleeve is free to revolve on the shaft 7 carried -n'bearings Specification ofLetters Patent. Patented June 28, 1921.

Applicatin vfiled May 9, 1917.y Serial No.l 167,578.,

v9, 10 and 11. Thel gripping element 12 ofl the clutch 6 is prevented from turning on the shaft 7 by means ofra'feather. When the clutch is open, though the motor is run? ning, the shaft 7 will `not revolve. When the clutch isclosed, 'and the motor is rnnning, the shaft 7 will revolve. This arrangement is not more fully illustrated as it 1s one 1n common use in power transmission. For the same reason the full clutch rigging, such as levers, pivots, are not shown.; the grooved portion 13 being suficientto indicate the sliding part of the clutch.v The.

ratio of theshaft and rmotor speeds is the same as that of the worm gearing..`

Upon the shaft 7 is mounted the` gear 14,

engaging with the gear 15 which is carried on a countershaft 16 mounted in bearings 17, 17. The gearlis preferably feathered to the shaft, so that it maybe slidout of engagement with the gear 7 afterv withdrawing the securing pin or set screw 18.'

Also mounted'on the shaft 16 lis the gear 19, which engages with another gear 20, the function of which will be explained later.

Slidably mounted `on the. shaft 7 is a sleeve 21, which'maybe secured' in position by means of a locked screw 22, as shown in the detail drawing Fig. V. On the sleeve 21 are the gears 23, 24, 25, 26, and 27.A

` Below the shaft 7, and mounted'in bearings 28 and 29-see Fig. 'IIanddetail-Fig. V-is the shaft 30, on which are secured the gears 31, 32, 33, 34, 35, and 36. vThe gears not shown in engagement are arranged toV engage as follows: 23 with 31, 24lwith 32, 27 with 35, and 26 with 34. Gear 25, which is also mounted on the sleeve, 21, may,as shown, engage with gear 33. kGrear 36 engages at all times with the gear 40; InA Fig.

lV fthe teeth of the gears Vare not shown. In

stead, the gears are shown bounded by their v pitch circles, so that the relation between one gear and another may be readily seen.

Motion being. imparted to the shaft 7 in the direction show n by the arrow, fixedv gear and 40 in the same direction as the shaft 7 and consequently in the same Vdirection as gear 20. As the gears 23, 24, 25, 26 and and their mates 31, 32, 33, 34, and 35 are of different diameters they will be revolved at a predetermined iXed speed, the gear 40 may be revolved at five different speeds, each one bearing a certain ratio to the speed of the gear 20. And no matter what the speed of r'the' motor, of 4the shaft 7 and of gear'20,

will not change. .1 Reference to `1 two gears-2O and 40 operate and control the -fwork spindle 5G- shown in this Fig. IV in :two' parts on account of its length. It is i5.-

maybe, the ratios between the speed of the gear and the several speeds of gear 40 Fig. IV will show' that the actually in one-straight piece.-

j 1 Gear 20-Lis mounted on a sleeve 41.which .z lis carried' by ball bearings'42 and 43, housed Y respectively in the bearing stands 44 and 45.

. Bearing 43 is of a thrust type to limit endwisemotion of the sleeve 41, and so allow A:for anice adjustment, ywith a minimum of A.; 'opening and a minimum of friction, between i .l't'hegear body and the adjacent bearing vv-wise movement `of the spindle is not conspindle.

covers 46 and 47. In the spindle 50 is a the same speed. At the same timethe endtrolled byV the gear -20 nor tongue 49. The sleeve 41 is a close sliding iit on the spindle 50, and, being mounted in ball bearings, willpractically prevent any side play in the Furthermorev should the bore of the Y.sleeve Wear larger, the sleeve can be readilyreplaced by a new one.

, Though any kind Vof good bearing may be- ;usedvfor the spindle sleeves, I prefer ball bearings because they permit of more accuratefadjustments with a minimum of frictionand a minimum of attention. The annulargrooves, such as 51, 51, shown in the body ,of gear 20, and in bearingrclosures. f46,47, etc., are to hold grease for the pur- Vpose of keeping grit or water out of the bearings. The bearings 42 and-43 are held 4in their respective places on the sleeve'41 1.by the lock-nuts'52 and 53. Similar lock-y nuts are shown securing other ball bearings.y Attachedto the bearing cover 46 and to the f gear 20, and elsewhere, are shownfclt oi" leather washers 54 heldin place by means of grings, 55, in turn Aheld by screws or-bolts. The object of these washers is to prevent as far as possible dust from entering be- -tween rotating and stationary parts.

vGear is rigidly attached to the sleeves 57 and 58, which are bored a close Vrunning kfit )fory the spindle 50. These two sleeves are carried in the bearings 59 and 60; housed .respectively in the stands and 61. .62

#and63 are bearing closures. Endwise mo- Vblock '66, bolted to stand 61.

tion ofV the gear 40 is prevented by the thrust bearings 64 and 65, acting against the thrust The end of the spindle is protected by means of the cover 67. The openings 68 in'the several lstands and the end cover are forlubrication.

Set in the hub of gear 40, and secured by means of a screw 69, is the nut 70, engaging a thread cut on the spindle 50. For the present it will be suliicient to note that if rotation of the spindle is prevented, rotation of gear 40 will give the Spindle'endw-ise movement. Also, if at the same time the geark 20 transmits rotary motion'to the spindle,

' the said spindle will then rotate and also have endwise movement; except when gears 20'and 4() have the same rotary speed.: Hereinafter the connection between the Vgears shown in Fig. IV and the two motions of the spindle 50 will be further explained.

VThe work carrying end of the spindle 50 is shown in the upperl part of Fig.=-IV.

This part of the spindle 50 is a sliding-fit in the sleeve 75, Vwhich is carried in bearings 76 and 77, held in place by lock-nutS78, 79,

and'mounted in thel housing 73 which V'forms appart of the stand 44. The housing terminates with the closure 74.

Outside the closure 74 and rigidly'secured to the spindle 50 is a head 80, to which is screwed an annular piece 81 carrying a sleeve 82 of sufficient length to protect fromqdust the opening between the closure 74 and the head 80 throughout the movement of the spindle 50. The head 80 isv securedfagainst endwise movement by means of the collar 83. 84 and 85 are ring oilers. At 86 is shown an oiling device consistingofa bent pipe which, as the sleeve revolves,y willi pick u oil from the bottom'of the housing 73, an allow it to drain through the sleeve 75 on to the spindle 50. The holes 87 will allow oil picked un by the ring 84 to pass through to thefspindle. Y l The work to be ground is shown at 90, and in this case consistsl of a hollow cylinder having chased-on its outer surfacefa spiral thread., the edge or point of which it is my object to grind.

The work having an inner cylindrical surface is held on vsuitable cone shaped .heads 91 and 92. vThe head 91 is attached to a sleeve 93 which is a close fit on the spindle 50. The head 92 is bored to slide closelyon the other endof the sleeve 93. At 94 `isa lock-nut for drawing the head 92 up on the `sleeve 93,'and soy locking the work 90 inv position and concentric with the spindle 50.

`of work heads .and sleeves, all set up with work, ready for attachment to thespindle.

It will be noted that the sleeve 93, with the -It also enables me to rotate the work aroundthe spindle,-for adjustment tothe grinder,

without endangering'their concentricity.`

The work heads are secured on the spindlev .0f,andfagainst the head 8 1, by means 0f' -thenut 95andwasher96, It will be vseenthat if nut 95 isslackened, the work head may be rotated- Aand that if mitr9'ie re-L 4r"gear 20 will be three'seventhsofthe rotary moved, the Work may elsobe removed- Sliding on vertical guides at one end 0f the bed 1 is the knee 100r` (see Figs. -Ifand II).

Fig. IV) is of the same pitch diameter-'as Y j rwhich is adjustableverticallyjby means 'of the screw101-workingin` the fixed nut 102 and journaled in thebearing 103. The screw lOl-has at its upper end the worm wheel 104 which is engaged by the worm 10.5v mounted on a shaft carried in bearings 106 and 107 "and provided with lthe hand wheel 108 and dial-109. y

' wheel 110 mounted ona shaft which maybe;l

On the knee 100 is carried the grinding driven by pulleys and belts from Overhead lines, or by means of an electric motor, asv

shown at 1.11y in Fig. I. The motor is emitted i more clearly seen. The motor 111 is preferably mounted on a bracket 112 which is pivotedY on the knee 100 at a point exactly beneath the center of the ,abrasivel Wheelv 110. In Fig. I the bracket 112 is shown pivoted at- 113; but whenlthe work shown at 90 is. in

y processv of grinding, the bracket 112 is piv oted immediately under the centerline of thej` spindle 50, and a little in advance of the end'of the 'work 90, at apoint, 114 indicated@ by the head `of thearrow in Fier. II. Also..

asshown inv detail in Ihus, as the work, 90 is advanced by the movement of the 'spindle 50 its center linejintersects a' vertical line dropped from the center of theabras-ive short a length as is practicable, the pair hav` wheel-110.A Y

AAs shown in Fig.Y VII the motor bracket H112 is provided with slots `115 and 116,

through which, and the holes 117, 118, 119

and 120A in the knee 100, shown'in Fig. VIII, tap bolts areused to clamp the motor bracketin the desiredpositions., The motor bracket 'clamped in position for operating on the Work 90 is shown inV Fig. IX. In this case line lof fthe motor may be set at various angles with the center line of the `Work the pivot 114, is a fixed point, and thel center spindle 50 for the grinding Vof work having :The work 90 carriedgbyspindle 5 0 has` a Vprovides for the grindin gef ,threadsA eut 6, 7, 8, 9 and 10 to the inch.v

:Referring to Figs. I andrV: The" shaft 7 iS driven by the meieltsiflth'reegh` the Clutch '.6 andworm gearing, 4, fat la given speed.

YThe .gear 14 has 'theY Same Speed the shaft 7; vGears 15 and `19'. are ofthe same diameter eS gear legend Consequently have the seele gember efrerelutione per miente clearance between bearing housings 45, 61, and other mechanisms. In the drawings the gear 20 is shown .tw'oand one third times greater in pitch diameter than gears 19, 15

and 14. 'Consequently the `rotary speed of speed of shaft 7.

Gear 40,' whi6h drives thenut 70, (see gear 2O-g1 and'gear 4 0 is driven by gear 36 on the shaft 30. Gear 36 is equal in pitch diameter to gears 14., 1 5 and "19. If the two shafts 7-and 30 were :given the same. speed, thetwo gears20 and 40 would also have the same speed of rotation; therefore' the spindle 50 and the 'nut 70 (in gear 40) would have the same rotary speed, and there would be. nel endwise movement imparted t0. the

In order to grind a spiral thread on the Work 90, .endwise movement is necessary, and proportional to the pitches. ofthe thread,

which weI have taken as 6, 7, 8, 9, and 10 to the. inch. To follow these Vpitches it is necessary to give to the gear 40 different rotary speeds having definite relations to the rotary -Speed of; the gear 20. This I do through the. gears 23 24, 25, 2 6, 27, and gears 31, 32, 33,

34, 4and 35, which, as, before stated, engage with one1 another afs follows -23 with 31, 24;,With 32, 25 with 33, 26 with 3 4, and27 V.With-35; the gears 23 to 27 being mounted von a; sliding sleeve, eathered tothe drive shaft 7', andwhich may be slid tothe right or to In 'order .that these gears may occupy as.

ing. the greatest ratio is placed between the other pairs, two. being on eitherA side of it;

yand the pairs having the two smallest ratios arev placed one at each end of the line. (Note that the gear 36 is not a change gear, but is a fixed gear driving gear-'40, and located whereshown to enable me to conveniently place gear 40. Ity is not a consideration in the "explanation of the arrangement and" jfunctione. 0f the change gearaexcept as impirllgmotiofllf IOm the Shaft 3 0 to the gear 40,)- 'lhis arrangement. allows clearance Abetween all gears except the engagingpair, ves well es' a saving of space and material.

" To grinigl spiral threads the work mus-t rstbe given a rotary motion to give a desirable grinding speed; that is the speed, in

leedf per minute, atI Whichl the Vthread is presented to the action ofthcabrasive.

er 1 0- tethe inch, for every completey revelu` The work; must at, the same ti'mebe advanced to-V the left. t0 bring the. several pairs of gears lintoengagelnenti.

\ -tionof the workthe-said work must be ade; "..vance'd 1/6, 1/7,`1/8,f1'/9for1/10vof an inch., VThe same of course applies tov 'the workV -vances per 4revolution in thisy gearing shown inrFigs. I, Il?, I I f designed. Note also' that no .matter/what- -the speed ofthe Vshafty 7 ,or of the motor 3,- the requiredrratios between the speeds 10 t If 'the .spindle 50be rotated,thenut meanwhile being stationary', orfif` the nut '70f jzbefrotated andthe spindle Obeing st'ationary, lthe 'lengthwise lmovement or advance of the spindle will equal the pitch of the screwl spindle50, andwtov producel the lstated 'adofthe gears and 40 will be preserved. f

f thread,lbyvthe'number of revolutionsf'the ydirection of advance depending. upon thewhand of the screw thread, or uponthe direcwithv a righthand thread, and when the Workn tion ofrota'tion` ofthe /spindlefor the nut. The burs to be ground are usually provided is to move from right to left-referringto Fig.y I'--the` yspindle is given a right hand roe tation, and vice versa. *Observed from the `right end of the machine'infFigI, `a right handed motion isclockwise.v l'Also the' .screw thread-lonV the spindle be right"-1 'handed, land bothV gears? 20 and^40 bere-'f' `volved clockwise, the spindle will move fromvvv Vleft 'to right so long a's-th'e revolutions yper ininute'of'lt'hegear l410 are less than those ofl gear 20,.`for clockwise rotationI of gearV 40' y either alone," or with, but ata greater speed than Vgear 20will cause the 'spindleto move, from left to right.y We "cannalso 'causethel 'l spindle to move tothe right bylcausing the:

' gears'20 ,and 40 yto rotateh anti-clockwise.

- lThe :advance of' the spindle 50 perfrevolu` tion depends upon the relation-between the rotative speeds of the gears 20 and 40,)and

'- from the above explanation it vcanbe shown that the advance is equal tothe pitch ofthe g. screw yminus fthe said pitch multiplied by the ratio of the rotary'speed ofthe gear 40 to that-of the gear 20; and if A'is the ad-y -vance, P thefscrew pitch, and R1 .they gear f ratio, then A::P(1-R1). #If vRzfis the ratio f` of the gear 20 to gear 19, and gears 15 and l4are equal'andalso eqa'l to Vgear 36 which has a'ratio to4 gear .40

' theV gears-20: and 40 are'falikelinfmsize,1and gears 19, 15, 14,36are alike, that-no matter @what size we give to"gears`20 `and 40and-to 19, 15,114, 36,the-formula for jthe Vadvance 36 are alike-in size, thenlthe ratio of the speeds of shafts 71'an`d '30 'must' bethe same as thefdesired speed `ratios of the gears 2() v and40; so we find that 'for an the spindle 50 the formu a*l `may be advance of A:P(1-R,); in which It,v represents the 10 threads, 3/5.` v Y AManifestly if thepitch' o f the screw equals diate the extreme rates of advance, thenmo "less than any rate of advance for which'the"k ratio of anyone of the pairs of. gears'on `shafts `-In andBO; and this formula may also yto `provide suitable change l gears ongthe .7 lrfsleeve 21 and` shaft 30', lwhich: maybe made Vas long as necessary. In the draw-ings I `have shownVY the gearingl oirV sleeve 21' and shaft 30 'as fdesi'gned for yinding threads fromk 6 to `10 pe'rinch.- y extending theY sleeve'and shaft other gears could be added forV other threads. l "'The advance per' revolution rof 6 threads required'gear "ratios for the several threads lare for 6 threads, 1/3; for .7 threads, 3/7

for 8 threads, 1/2; for

Ione Vof the desired rates'of advance, either one of the gears 20 or 4() mustnot revolve. And if the pitch of the screw'is intermetion of l'thegearingin twofdirections for` one .dlrection of advance would ,be necessary...

-Thereforeto make the arrangement assimple as'possible, I use a screw pitch which is machine iis designed. @This allows positive vmotion of all gearing, andalso motion in' only one direction 'of gearing for, advance of thefspindlewin a'givendirection'.' t Having` established lthel gear ratios, fthe centers between the sleeve .21 and shaft 30 are chosen so thatl gears of the required sizes may be used. This distance must. be suchythat each pair of gears will have theV de-r sired ratio, Vand also a whole number ofw1 teeth. Addingfiogether the numerator :and denominator in the gear ratios found above wehave, 4,'10,3, 14, and 8'. Each ofthese numerals is a stand'ard'pitchor a factor of a factorof a Whole number, fory instance 1%,

2, 2%, 3 3&4., 49,, 5, etcjJ-f. But there are practical limits set by -the diameter of the sleevem 21 and they available space in the machine andIhavev found centers of 3%, Vusing a suitable tooth pitch for each pair/'of gears,

In Fig. :III is showna bur havingspirall teeth or cuts),` Bur's are also made with`f'125 straight,and with vdiagonal cuts; 'and combinations of rvspiral and straight, and of difagonali'and straight cuts are also used to form interrupted teeth of various Llengths and pitches. The diagonal and straightcut'` 180 and so'ornBy .i

.fusing the form-ula R4: 1 a?, VI d'tha .th S5 9 threads, 5/9; for Y i Y y ...90

filo

y standard pitch; sof forthe distance between?-= ,"centersfwe can use any whole number, or a in. .bearings and Ahaving a ,screw.;.threaded.L

. portion, a rotary nut engaging the threadv on the spindle, "and confined as to motion in a.. horizontal :plane`,umeans "for: rotati'ng'fthc.l l spindle, meansVl for .rotatingytheenun `'and differential means for controlling. the speed f of rotation of the nut.y .f Y;

101 Thecombinationfof-a spindle mou-nted ink bearings and having .a screw-threaded portion,- aalrotary nut engaging. thenspindle Vthread and adapted on being. rotatedy `with reference-.tolthe'. spindle. to advancezthe spindle,v means .for rotating the .spindle,'

means :for rotating the nut, ydifferential vmeans controlling the relation between the rotation of thespindle and of thev nut, 4.said differential being equal to' unity fminus the ratio of the desired spindlev 'advancev per revolution tothe pitch of the-spindle thread.

' 11. A differential controllingthe'relation. betweenl the rotation and the rectilinear.

. movement vof Va-:shaft, Aand, consisting ofv means for rotating the shaft, rotary threaded means engaging the shaft to give endvvise,`

motion 'to the shaft, geared-means for changing the Yspeed of the rotary'threaded means 4fper'revolution.of the shaft,`f thev ratio of said'geared means being .equal to unity-minus the ratio between the'desired` rectilinear motion of the-shaft perrevolution,j and the pitchof the threaded means.

. 12.` Thecombinationof a spindle mounted in bearings,and yhaving'1a1screw-threaded ortion, ak f rotary nut engaging; the thread of the spindle, and confined asto motion. in

a horizontal iplane; means for rotatingthe i spindle in -the nut, 'and differential means motions ofthe spindle. f.

actuating the spindle rotating meansyand also rotating the nut and' adapted Ato Achange the ratio betweenV the rotary and 13. The combination of arspindle mounted in 'bearings and having a' threaded portion-,1'

a nut-engaging the threadofthe spindle;

means for rotating the spindle,V -mea'ns--forl rotating'the nut, and differential: means for I changingthe relative speeds of! the sha'ftfroi. tating 'meansan'd the nutrotating'meanf's to change the-ratio betvveen the rotary and rectilinear motions of th'efshaft.:4 i 1 l 14.' "The 'combination' of a shaftvv mounted i l in loearings,`r `means 'for rotating" the shaft,v

means for imparting rectilinearmotion to the shaft,l a second-shaft, a gearmountedon the second shaft and arranged to actuat'etheV meansfor imparting :rectilinear motionl to the frstwshaft, af set offgearsof different pitch diameters mountedr on `said second shaft, a third shaft parallel' to'thesecond l6V0`shauft, a sleeveslidably mountedland feath-ff ered on the thirdshaft, a set of lgears mountrectilinear ed' on lthe sleevefand each-one beingil adapted.

to engage oneoffthe` gears .on :thezs'eolond .of (gears A will-'be inengagementiat, one; time', an

-means for rotating the vvthird shaft.; zal L.` 15,.ThecombinationLof'aashaft mountedg.: .in bearings,'means for rotatingthelshaftycq shaft,A and'ysoxzfarranged that only one pair v means; for .imparting .v-.lectilinear motion n-.to .1

the shaft,v a second shaft, a gear mountedY on l Vthe second shaft and arrangedto actuate the i- .i

means for imparting f-rectilinear' motion. to the first shaft; a., set of gears .of different 1,-.

pitch .diameters mounted on said'. second Ashaft, av third g. shaft parallel to .thel second 1 shaft; a sleeve yslidably."mountedvv and feathfw.;

eredi on-the thirdy :shaftgl al..l set: of i gears. 'i mounted onthef-sleeve and eachone..being5. i. adapted to engage 'one of 44the gears. fonithe second shaft, and so arranged that ,only one.v pairvof-gears Will'berinengagement at onel f r roportime,..each air of: gearsbeing so 1/10;l "1; :.respectively51f` per revolution joflthel 85 first'sh'afnandmeans for rotating thethird f?. i '.Shafl'a ifi' ffur" 4 16. The combination of'a shaft Vmounted` 'f `inbearings, means'forrotatinggthe .shaf.t,:

means v for imparting vrectilinear? motion to on the .second-.shaft and ar-ranged to actuate 1 the." means for imparting rectilinear motion pitch -rdiameters `Inounted. onffsaid ,1 second to the first shaft, a set of gears of different-f shaft;l the .r largest gear being.V .plaoedei themiddleof the ro'w of gears; andtherema-in- `1:2; i'

ing gears being located on' either lside vvof lthe: 1- v largest gear Vand indescending sizesga third -f shaft paralleli to: the second Shaft',y af -sleeve :1100 slidably ,mounted "and :feathered` onftle :third v 1 I :shaftya set of 'gears .mounted on the isleeve andeach onebei'ng adapted to engage one?V` andf to move r inl `the :direction of vits axis,

of thege'ars .ontheseoond shaft, `and-Iso are'.l f' ranged ikthat only :one pair `.of 'gearsfewill @be r 1n engagement a'tfone ftimeand-,m'eansfo f 1' The combination of a led'11i-"fixed bearings and adapted-$0 www `1110 mean'SfOr securing thevvork onthespindlefzfE` meansv for frotatingwthe; fspindle,. and4 rrota.-

table means for advancingthe spindle at. aai: speed havinga predeterminedxrelation1to..`` K

Y Injtestimony*whereoflfhave hereunto'af-l ifxedi my signature ,inthe presencefof. two?- .lthespeed ofjrotationofthe-spindleffz" f HHnDWIoim 

